Swelling and shrinkage due to moisture-change is one of the characteristics of the expansive soil,which is similar to the behavior of most materials under thermal effect,If the deformation is restricted,stress in expa...Swelling and shrinkage due to moisture-change is one of the characteristics of the expansive soil,which is similar to the behavior of most materials under thermal effect,If the deformation is restricted,stress in expansive soil is caused by the swell-shrinking.The stress is defined as "moisture-change stress" and is adopted to analyze swell-shrinkage deformation based on the elasticity mechanics theory.The state when the total stress becomes equal to the soil tensile strength is considered as the cracking criterion as moisture-change increases.Then,the initial cracking mechanism due to evaporation is revealed as follows:Different rates of moisture loss at different depths result in greater shrinkage deformation on the surface while there is smaller shrinkage deformation at the underlayer in expansive soil;cracks will grow when the nonuniform shrinkage deformation increases to a certain degree.A theoretical model is established,which may be used to calculate the stress caused by moisture-change.The depth of initial cracks growing is predicted by the proposed model in expansive soil,A series of laboratory tests are carried out by exposing expansive soil samples with different moisture-changes.The process of crack propagation is investigated by resistivity method.The test results show good consistency with the predicted results by the proposed theoretical model.展开更多
Cytokinin is a critical growth regulator for various aspects of plant growth and development. In Arabidopsis, cytokinin signaling is mediated by a two-component system-based phosphorelay that transmits a signal from t...Cytokinin is a critical growth regulator for various aspects of plant growth and development. In Arabidopsis, cytokinin signaling is mediated by a two-component system-based phosphorelay that transmits a signal from the receptors, through histidine phosphotransfer proteins, to the downstream response regulators （ARRs）. Of these ARRs, type-A ARR genes, whose transcription can be rapidly induced by cytokinin, act as negative regulators of eytokinin signaling. However, because of functional redundancy, the function of type-A ARR genes in plant growth and development is not well understood by analyzing loss-of-function mutants. In this study, we performed a comparative functional study on all ten type-A ARR genes by analyzing transgenic plants overexpressing these ARR genes fused to a MYC epitope tag. Overexpression of ARR genes results in a variety of cytokinin-associated phenotypes. Notably, overexpression of different ARR transgenes causes diverse phenotypes, even between phylogenetically closely-related gene pairs, such as within the ARR3-ARR4 and ARR5-ARR6 pairs. We found that the accumulation of a subset of ARR proteins （ARR3, ARR5, ARR7, ARR16 and ARR17; possibly ARR8 and ARR15） is increased by MG132, a specific proteasomal inhibitor, indicating that stability of these proteins is regulated by proteasomal degradation. Moreover, similar to that of previously characterized ARR5, ARR6 and ARR7, stability of ARR16 and ARR17, possibly including ARR8 and ARR15, is regulated by cytokinin. These results suggest that type-A ARR proteins are regulated by a combinatorial mechanism involving both the cytokinin and proteasome pathways, thereby executing distinctive functions in plant growth and development.展开更多
The cracking patterns of a thin sheet with a pre-existing crack subjected to dynamic loading are numerically simulated to investigate the mechanism of crack branching by using the FEM method.Six numerical models were ...The cracking patterns of a thin sheet with a pre-existing crack subjected to dynamic loading are numerically simulated to investigate the mechanism of crack branching by using the FEM method.Six numerical models were set up to study the effects of load,tensile strength and heterogeneity on crack branching.The crack propagation is affected by the applied loads,tensile strength and heterogeneity.Before crack branching,the crack propagates by some distance along the direction of the pre-existing crack.For the materials with low heterogeneity,the higher the applied stress level is and the lower the tensile strength of the material is,the shorter the propagation distance is.Moreover,the branching angle becomes larger and the number of branching cracks increases.In the case of the materials with high heterogeneity,a lot of disordered voids and microcracks randomly occur along the main crack,so the former law is not obvious.The numerical results not only are in good agreement with the experimental observations in laboratory,but also can be extended to heterogeneity media.The work can provide a good approach to model the cracking and fracturing of heterogeneous quasi-brittle materials,such as rock,under dynamic loading.展开更多
Objective To investigate the variation of auditory evoked potential P50 in first-episode schizo- phrenia. Methods P50 was recorded from 66 schizophrenics and 92 normal controls with American Brova instrument, and asse...Objective To investigate the variation of auditory evoked potential P50 in first-episode schizo- phrenia. Methods P50 was recorded from 66 schizophrenics and 92 normal controls with American Brova instrument, and assessing their psychotic symptoms with PANSS. Results Compared with NC, schizophrenics showed sensory gating deficit, reflecting by increased S2/S1 ratio (NC: 42±21% , Sch:81±40% ,P <0. 01). No significant correlation was found between PANSS score and the three markers for assessing the sensory gating, such as the S2/S1 ratio, S2-S1, and 100 (1 -S2/S1) (P > 0. 05). Schizophrenics showed no differences with P50 markers between the 5 weeks and 12 weeks of treatment. Conclusion P50 might be biological trait marker of schizophrenia.展开更多
Gently dipping fractures subjected to river incision are widely distributed on rock slopes.In this paper,a rock slope on the Nujiang River(China)is investigated to study the role of gently dipping fractures in the roc...Gently dipping fractures subjected to river incision are widely distributed on rock slopes.In this paper,a rock slope on the Nujiang River(China)is investigated to study the role of gently dipping fractures in the rock slopes evolution.Detailed field surveys indicate that gentle fractures are concentrated in four main zones.Moreover,the kinematics of the fracture system suggest that the genesis of these fractures can be synthesized into a progressive evolution model.This model indicates that the joints begin with the formation of an array of en echelon cracks that are subjected to continued crack elongation and shearing before ultimately approaching one another and interacting to form a complex joint system.Geomechanical analysis is performed to reveal the mechanisms of this genesis,and three main fracture patterns are identified based on the slope stress and are classified with respect to the slope evolution.Based on the detail field investigations and the evolutionary history of the river valley,we propose that intermittent incision by the river was the main factor contributing to the concentrated distribution of gently dipping joints.展开更多
As a critical apoptosis executioner, caspase-3 becomes activated and then enters into the nucleus to exert its function. However, the molecular mechanism of this nuclear entry of active caspase-3 is still unknown. In ...As a critical apoptosis executioner, caspase-3 becomes activated and then enters into the nucleus to exert its function. However, the molecular mechanism of this nuclear entry of active caspase-3 is still unknown. In this study, we revealed that easpase-3 harbors a crm-l-independent nuclear export signal （NES） in its small subunit. Using reversecaspase-3 as the study model, we found that the function of the NES in caspase-3 was not disturbed by the conformational changes during induced caspase-3 activation. Mutations disrupting the cleavage activity or p3-recognition site resulted in a defect in the nuclear entry of active caspase-3. We provide evidence that the p3-mediated specific cleavage activity of active caspase-3 abrogated the function of the NES. In conclusion, our results demonstrate that during caspase-3 activation, NES is constitutively present, p3-mediated specific cleavage activity abrogates the NES function in caspase-3, thus facilitating the nuclear entry of active caspase-3.展开更多
近日,刊登在国际杂志Journal of Cell Biology上的研究论文中,来自莱斯特大学的研究人员揭示了他们在癌症机制研究上的进展,并且阐明了如何利用新疗法对癌症进行有效的靶向作用;研究者表示,这种解释细胞分裂的新机制或可帮助寻找癌症疗...近日,刊登在国际杂志Journal of Cell Biology上的研究论文中,来自莱斯特大学的研究人员揭示了他们在癌症机制研究上的进展,并且阐明了如何利用新疗法对癌症进行有效的靶向作用;研究者表示,这种解释细胞分裂的新机制或可帮助寻找癌症疗法的新靶点。研究者Fry教授表示,这两篇研究论文都为我们提供了新的研究线索,即细胞在分裂的过程中如何将适量的遗传物质遗传给子代细胞;文章中研究者鉴别出了一系列调节细胞分裂机制的关键步骤,同时也发现了一些新靶点,抑制这些新靶点或可阻断癌细胞的分裂。研究者的最终目的就是理解隐藏在细胞分裂背后的新的生物学机制，为开发有效的疗法来治疗患一系列癌症的病人提供帮助。展开更多
基金Project(2006BAB04A10) supported by the National Science and Technology Pillar Program during the 11th Five Year Plan of ChinaProject(51008117) supported by the National Natural Science Foundation of China
文摘Swelling and shrinkage due to moisture-change is one of the characteristics of the expansive soil,which is similar to the behavior of most materials under thermal effect,If the deformation is restricted,stress in expansive soil is caused by the swell-shrinking.The stress is defined as "moisture-change stress" and is adopted to analyze swell-shrinkage deformation based on the elasticity mechanics theory.The state when the total stress becomes equal to the soil tensile strength is considered as the cracking criterion as moisture-change increases.Then,the initial cracking mechanism due to evaporation is revealed as follows:Different rates of moisture loss at different depths result in greater shrinkage deformation on the surface while there is smaller shrinkage deformation at the underlayer in expansive soil;cracks will grow when the nonuniform shrinkage deformation increases to a certain degree.A theoretical model is established,which may be used to calculate the stress caused by moisture-change.The depth of initial cracks growing is predicted by the proposed model in expansive soil,A series of laboratory tests are carried out by exposing expansive soil samples with different moisture-changes.The process of crack propagation is investigated by resistivity method.The test results show good consistency with the predicted results by the proposed theoretical model.
文摘Cytokinin is a critical growth regulator for various aspects of plant growth and development. In Arabidopsis, cytokinin signaling is mediated by a two-component system-based phosphorelay that transmits a signal from the receptors, through histidine phosphotransfer proteins, to the downstream response regulators （ARRs）. Of these ARRs, type-A ARR genes, whose transcription can be rapidly induced by cytokinin, act as negative regulators of eytokinin signaling. However, because of functional redundancy, the function of type-A ARR genes in plant growth and development is not well understood by analyzing loss-of-function mutants. In this study, we performed a comparative functional study on all ten type-A ARR genes by analyzing transgenic plants overexpressing these ARR genes fused to a MYC epitope tag. Overexpression of ARR genes results in a variety of cytokinin-associated phenotypes. Notably, overexpression of different ARR transgenes causes diverse phenotypes, even between phylogenetically closely-related gene pairs, such as within the ARR3-ARR4 and ARR5-ARR6 pairs. We found that the accumulation of a subset of ARR proteins （ARR3, ARR5, ARR7, ARR16 and ARR17; possibly ARR8 and ARR15） is increased by MG132, a specific proteasomal inhibitor, indicating that stability of these proteins is regulated by proteasomal degradation. Moreover, similar to that of previously characterized ARR5, ARR6 and ARR7, stability of ARR16 and ARR17, possibly including ARR8 and ARR15, is regulated by cytokinin. These results suggest that type-A ARR proteins are regulated by a combinatorial mechanism involving both the cytokinin and proteasome pathways, thereby executing distinctive functions in plant growth and development.
基金Project(50820125405)supported by the National Natural Science Foundation of ChinaProject(51121005)supported by the National Natural Science Foundation of China
文摘The cracking patterns of a thin sheet with a pre-existing crack subjected to dynamic loading are numerically simulated to investigate the mechanism of crack branching by using the FEM method.Six numerical models were set up to study the effects of load,tensile strength and heterogeneity on crack branching.The crack propagation is affected by the applied loads,tensile strength and heterogeneity.Before crack branching,the crack propagates by some distance along the direction of the pre-existing crack.For the materials with low heterogeneity,the higher the applied stress level is and the lower the tensile strength of the material is,the shorter the propagation distance is.Moreover,the branching angle becomes larger and the number of branching cracks increases.In the case of the materials with high heterogeneity,a lot of disordered voids and microcracks randomly occur along the main crack,so the former law is not obvious.The numerical results not only are in good agreement with the experimental observations in laboratory,but also can be extended to heterogeneity media.The work can provide a good approach to model the cracking and fracturing of heterogeneous quasi-brittle materials,such as rock,under dynamic loading.
基金Supported by the National Nature Science Foundation of China (30470626)
文摘Objective To investigate the variation of auditory evoked potential P50 in first-episode schizo- phrenia. Methods P50 was recorded from 66 schizophrenics and 92 normal controls with American Brova instrument, and assessing their psychotic symptoms with PANSS. Results Compared with NC, schizophrenics showed sensory gating deficit, reflecting by increased S2/S1 ratio (NC: 42±21% , Sch:81±40% ,P <0. 01). No significant correlation was found between PANSS score and the three markers for assessing the sensory gating, such as the S2/S1 ratio, S2-S1, and 100 (1 -S2/S1) (P > 0. 05). Schizophrenics showed no differences with P50 markers between the 5 weeks and 12 weeks of treatment. Conclusion P50 might be biological trait marker of schizophrenia.
基金financially supported by the National Natural Science Foundation of China (Grant No. 41521002 41130745+2 种基金 41272330)State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No. SKLGP2016Z015)supported by the Funding of Science and Technology Office of Sichuan Province (Grant Nos. 2015JQ0020)
文摘Gently dipping fractures subjected to river incision are widely distributed on rock slopes.In this paper,a rock slope on the Nujiang River(China)is investigated to study the role of gently dipping fractures in the rock slopes evolution.Detailed field surveys indicate that gentle fractures are concentrated in four main zones.Moreover,the kinematics of the fracture system suggest that the genesis of these fractures can be synthesized into a progressive evolution model.This model indicates that the joints begin with the formation of an array of en echelon cracks that are subjected to continued crack elongation and shearing before ultimately approaching one another and interacting to form a complex joint system.Geomechanical analysis is performed to reveal the mechanisms of this genesis,and three main fracture patterns are identified based on the slope stress and are classified with respect to the slope evolution.Based on the detail field investigations and the evolutionary history of the river valley,we propose that intermittent incision by the river was the main factor contributing to the concentrated distribution of gently dipping joints.
基金Supplementary information is linked to the online version of the paper on the Cell Research website.Acknowledgments We thank Prof Jian Wang （Shanghai University, Shanghai） for his valuable revision and discussion. This work was supported by grants from the National Natural Science Foundation of China （30700411）, Shenzhen Bureau of Science Technology and Information （SZKJ-2006018, SZKJ-2007012）, Shenzhen Nanshan Bureau of Science Technology and Information （2008036） and Shenzhen Key Laboratory Advancement Scheme.
文摘As a critical apoptosis executioner, caspase-3 becomes activated and then enters into the nucleus to exert its function. However, the molecular mechanism of this nuclear entry of active caspase-3 is still unknown. In this study, we revealed that easpase-3 harbors a crm-l-independent nuclear export signal （NES） in its small subunit. Using reversecaspase-3 as the study model, we found that the function of the NES in caspase-3 was not disturbed by the conformational changes during induced caspase-3 activation. Mutations disrupting the cleavage activity or p3-recognition site resulted in a defect in the nuclear entry of active caspase-3. We provide evidence that the p3-mediated specific cleavage activity of active caspase-3 abrogated the function of the NES. In conclusion, our results demonstrate that during caspase-3 activation, NES is constitutively present, p3-mediated specific cleavage activity abrogates the NES function in caspase-3, thus facilitating the nuclear entry of active caspase-3.
文摘近日,刊登在国际杂志Journal of Cell Biology上的研究论文中,来自莱斯特大学的研究人员揭示了他们在癌症机制研究上的进展,并且阐明了如何利用新疗法对癌症进行有效的靶向作用;研究者表示,这种解释细胞分裂的新机制或可帮助寻找癌症疗法的新靶点。研究者Fry教授表示,这两篇研究论文都为我们提供了新的研究线索,即细胞在分裂的过程中如何将适量的遗传物质遗传给子代细胞;文章中研究者鉴别出了一系列调节细胞分裂机制的关键步骤,同时也发现了一些新靶点,抑制这些新靶点或可阻断癌细胞的分裂。研究者的最终目的就是理解隐藏在细胞分裂背后的新的生物学机制，为开发有效的疗法来治疗患一系列癌症的病人提供帮助。
